1. Field of the Invention
The invention relates to a method for pre-cleaning parts, which are made of plastic and to which foreign bodies to be removed are stuck, as part of a recycling process, more particularly for removing foreign bodies disposed on parts made of plastic, preferably for removing labels, dirt, etc. disposed on used plastic bottles such as PET bottles.
The invention further relates to an apparatus for applying the method of the invention.
2. Description of Related Art
Equipment and methods for treating plastic waste (e.g., PET bottles) are known from practical experience. Here, any dirt is removed usually by subjecting the plastic waste to a wet-washing process.
Even a hot-washing process is often required with the addition of cleaning chemicals such as caustic soda solution, NaOH, etc. Here, the washing medium is constantly reconditioned, which results in high outlay and considerable environmental pollution if the washing medium is discharged as waste water on completion of the washing process.
One particular problem is the impurities or foreign bodies disposed on plastic bottles such as the so-called PET bottles. For recycling the PET bottles, it is necessary to remove the labels that are made of a different material than the bottles and are mostly printed. They are often made of PVC and can be removed only with difficulty in a conventional washing plant. Moreover, other foreign bodies such as stones, glass, small pieces of metal, etc. that are not collected by an overband magnetic separator remain stuck to the PET bottles. These foreign bodies must also be removed from the plastic to be recycled.
Furthermore, it is significant that the foreign bodies stuck to the PET bottles are often abrasive components. If these abrasive components are not removed before the comminution or grinding process of the PET bottles, they result in a considerable amount of wear of the mill. Furthermore, any residual content of the bottles must be removed since the sticky sugared water results in disturbances during the further processing and recycling. Moreover, residual liquid in the bottles stresses the wastewater treatment plants.
The object underlying the present invention is therefore to specify a method and an apparatus for pre-cleaning parts made of plastic as part of a recycling process, as a result of which it is possible to recycle plastic without any problems. The invention aims to reduce the contamination of the water cycle to a minimum.